The present invention relates generally to retractable hypodermic syringes, and more particularly to a retractable hypodermic syringe having a needle carrier adapted for releasably attaching a needle cartridge thereto prior to use. The present invention relates further to such a hypodermic syringe having means for retarding the unlatching of the needle carrier from the mounting collar of the syringe barrel during installation or removal of a needle cartridge, and still further to an invertible protective cover adapted at one end for sheathing the hypodermic needle prior to use, and at the other end for releasably attaching to and enclosing, or otherwise closing, a hub of the mounting collar at an end of the syringe barrel in the absence of a needle cartridge.
In the past, needle stick injuries suffered by medical personnel and others in the course of using hypodermic syringes have presented a serious problem. Serious diseases such as hepatitis and AIDS may be transmitted by needle stick injuries, resulting in the needless suffering, and possibly even in the death, of the unfortunate victims. Of late, the onslaught of AIDS has resulted in needle stick injuries posing an even greater health hazard because of the virtual certain death, at least insofar as research to date indicates, of the injured person if he or she contracts the disease.
In order to minimize the risk of needle stick injuries, retractable syringes have been developed which enable the retraction of the needle into the barrel of the syringe following use and prior to disposal. The movement of the needle in the retracted position is typically limited such that normally it will not again protrude from the barrel, and normally will not again come into contact with a health care worker or other person. Retraction and retention of the possibly contaminated needle into the barrel thus protectively isolates the needle and keeps it out of further human contact under normal circumstances. Such a retractable syringe is shown, for example, in U.S. Pat. No. 4,747,830, issued May 31, 1988, to Walter W. Gloyer and Frederick G. Bright, also the inventors herein, the disclosure of which is hereby incorporated by reference as if fully recited herein, including the references to and citations of the state of the art.
At times, persons having a need to use a hypodermic syringe will desire to select a particular size or shape of needle, such as one relatively longer or shorter than others he or she typically uses, or one having a larger or smaller diameter. Hypodermic needle cartridges have been used in the past for nonretractable syringes. It would be advantageous if a health care worker or other such person could simply select a needle cartridge having a needle of the desired size and shape and easily install it in a commonly configured retractable syringe body. This would afford the syringe user the flexibility of meeting his or her particular medical needs with a variety of needles but only a single inventory of syringe bodies, as well as the safety and protection that a retractable syringe provides against needle stick injuries, while assuring reliability in connection. Since only one configuration of syringe body need be manufactured for use with a virtually unlimited selection of needle cartridges, the savings in tooling and manufacturing costs would also be significant. Moreover, the manufacture of a common syringe body without a needle permanently attached would simplify the manufacturing process for the retractable syringe, since the hypodermic needle would not have to be installed during manufacture of the syringe body.
One type of hypodermic needle cartridge used in the past is adapted for threaded engagement in a pocket disposed on the syringe barrel. The pocket typically has a needle cartridge support member disposed at or near its center, which is sealingly received in a correlatively shaped bore in the body of the needle cartridge. The body of the needle cartridge in one such prior art cartridge arrangement is provided with a pair of diametrically opposed tabs which threadedly engage a pair of axially spaced apart helical threads in the pocket on the syringe barrel.
A hypodermic syringe needle typically is provided with a protective sheath for covering the needle prior to use of the syringe. With conventional non-retractable syringes, the protective sheath may be reinstalled on the needle following use, but such reinstallation also involves the inherent risk of a needle stick injury from improper or careless handling or the like of the needle, the sheath, or both. Sometimes the person attempting to reinstall the sheath may not be physically able to do so easily, as might be the case, for example, if the person were to suffer from arthritis, a nerve disorder, or other problem. Moreover, U.S. Center for Disease Control guidelines now prohibit the recapping of syringes with the needle covers after use.
Following use of a retractable syringe, there is no need to reinstall the protective sheath, so the risk of a needle stick arising from such reinstallation is eliminated.
There is another potential disease-causing contamination problem, however, in that the syringe barrel is left open following retraction of the needle, thereby permitting any excess fluid or residue left in the syringe barrel to leak out into the environment. For example, if the excess fluid or residue were to be a contaminated fluid or residue, there is a risk of the contaminating virus or bacteria contaminating other medical tools or equipment in the area, possibly infecting persons who subsequently come into contact with such tools or equipment or the syringe. The needle sheaths typically used in the past for covering the needles are incapable of being used to enclose the barrels of retractable syringes following use and retraction of the needles into the barrels, so as to prevent such leakage and environmental contamination. Although sealable containers have been used in the past into which used syringes can be placed for disposal, such containers are typically completely separate items which must be provided along with the syringes or kept on hand somewhere close at hand. This results in extra labor and materials costs to manufacture such containers, extra shipping costs to supply them to the users, and extra storage and handling costs on-site.
It is an object of the present invention to provide a retractable syringe with a common barrel configuration which will reliably accept a needle cartridge in which is mounted a needle of virtually any desired size or shape. It is another object of the present invention to provide such a retractable syringe with a needle carrier releasably latched into a mounting collar of the barrel and into which the needle cartridge is installed, and means for preventing or retarding unlatching of the needle carrier from the mounting collar during installation or removal of the needle cartridge. With this object, it is an object of the present invention to provide a retractable syringe on which a needle cartridge may be securely mounted such that the needle is firmly stabilized and supported in the needle carrier, and the needle carrier is securely latched in the mounting collar until such time as unlatching is desired. With these objects, it is an object of the present invention to provide a retractable syringe with a protective cover that will both cover the needle prior to use, and firmly enclose the end of the barrel in which the needle cartridge is mounted either prior to installation of a needle cartridge in order to prevent contamination of the barrel, or following use of the syringe and retraction of the needle in order to prevent leakage of excess fluid or residue from the barrel. As part of this object, it is an object of the present invention to provide such a syringe and cover which is durable, reliable, and easy to use. It is still another object of the present invention to provide such a syringe which is inexpensive and simple to manufacture.